Many structural assemblies have been developed to enable non-ambulatory patients, injured persons and the like to move over the surface of the ground. Conventionally, these structures have incorporated large side wheels used in combination with either leading or trailing wheels provided for stability. In many instances, the needs of a patient are not satisfied by such constructions since they provide for little more than movement of the patient or user over the ground. In many instances, particularly in the case of elderly patients or severely handicapped persons, a lifting mechanism is also required. To this end, the prior art has provided relatively complicated and therefore expensive structures which are difficult for a user to employ safely. In many such structures of the prior art, the lifting mechanism is apt to failure or, conversely, is so complicated as to require constant mechanical attention to enable safe and easy operation.